USGS Scientists Are Major Contributors to New Report on Sea-Level Rise

Above: Aerial photograph of northern Assateague Island and Ocean City, Maryland, from chapter 3 ("Ocean Coasts"), showing former barrier positions. In 1850, a single barrier island, shown outlined in yellow, occupied this stretch of coast. In 1933, Ocean City inlet was created by a hurricane and soon after was stabilized by jetties. By 1942, the barrier south of the inlet had migrated landward (green shaded area) in response to a drastic reduction in sediment supply. Such changes may become more widespread in response to future accelerated sea-level rise. Shorelines from Maryland Geological Survey; photograph from National Park Service. [larger version]

Global sea level is rising, and there is evidence that the rate is accelerating. Increasing atmospheric concentrations of greenhouse gases, primarily from human contributions, are very likely warming the atmosphere and oceans. The warmer temperatures raise sea level by expanding ocean water, melting glaciers and icecaps, and possibly increasing the rate at which ice sheets discharge ice and water into the oceans. Rising sea level and the potential for stronger storms pose an increasing threat to coastal cities, infrastructure, beaches, wetlands, and ecosystems. The potential impacts to the United States extend across the entire country: ports provide gateways for transport of goods domestically and abroad; coastal resorts and beaches are central to the U.S. economy; and wetlands provide valuable ecosystem services, such as filtering water, buffering storm surge, and providing spawning grounds for commercially important fish. How people respond to sea-level rise in the coastal zone will have potentially large economic and environmental costs.

A new report addressing these issues was recently released by the U.S. Climate Change Science Program. The report, titled Coastal Sensitivity to Sea-Level Rise: A Focus on the Mid-Atlantic Region, provides a detailed assessment of the effects of sea-level rise and examines multiple opportunities for governments and coastal communities to plan for and adapt to rising sea levels. The U.S. Environmental Protection Agency (EPA), the U.S. Geological Survey (USGS), and the National Oceanic and Atmospheric Administration (NOAA) prepared the report, with additional contributions from the U.S. Department of Transportation. Numerous authors from national, State, and local agencies and organizations, academic institutions, and private consulting firms contributed to the 300-page document, which describes potential changes to barrier islands, wetlands, other coastal habitat, and vulnerable species; societal impacts and implications of sea-level rise; decisions that may be sensitive to sea-level rise; opportunities for adaptation; and institutional barriers to adaptation. It also outlines current coastal policies in the mid-Atlantic region and implications for the other regions of the United States. Finally, the report discusses opportunities for natural and social science to enhance our understanding of the potential impacts of sea-level rise and society's ability to respond.

Although the issues apply to coastal regions across the country, the report focuses on the mid-Atlantic region of the United States, where rates of sea-level rise are moderately high, severe storms are fairly common, and a large extent of critical habitat (marshes), high population densities, and infrastructure exist in low-lying areas.

Sea-level rise can affect coastal communities and habitats in various ways, including submerging low-lying lands, eroding beaches, converting wetlands to open water, intensifying coastal flooding, and increasing the salinity of estuaries and freshwater aquifers. Some impacts of sea-level rise can already be observed along the U.S. coast, underscoring the immediate need for improving scientific understanding and the ability to predict the effects of rising sea level. Beginning to incorporate sea-level rise into coastal planning, in combination with the development of decision-support tools for taking further adaptive action, could lessen the economic and environmental impacts of sea-level rise on the United States.

Above: Diagram from chapter 4 ("Coastal Wetland Sustainability"), illustrating climate and environmental drivers influencing vertical and horizontal wetland development. The authors state, "It is virtually certain that tidal wetlands already experiencing submergence by sea-level rise and associated high rates of loss (e.g., Mississippi River Delta in Louisiana, Blackwater River marshes in Maryland) will continue to lose area in response to future accelerated rates of sea-level rise and changes in other climate and environmental drivers." [larger version]

Six of the new report's lead authors are USGS scientists: Donald R. Cahoon (Patuxent Wildlife Research Center, Beltsville, Md.), Dean B. Gesch (Earth Resources Observation and Science [EROS], Sioux Falls, S.D.), Benjamin T. Gutierrez (Woods Hole Science Center, Woods Hole, Mass.), E. Robert Thieler (Woods Hole Science Center), S. Jeffress Williams (Woods Hole Science Center), and K. Eric Anderson (retired). The USGS Office of Global Change recently recognized the authors' contributions to this more-than-3-year effort. Over the past several weeks, Pat Jellison, Chief of Global Change Research and Development, traveled to the authors' science centers to present them with STAR Awards and to address each center about the importance of USGS contributions to the U.S. Climate Change Science Program (CCSP). The new report is one of 21 climate-change synthesis and assessment products commissioned by the CCSP, which was established in 2002 to provide the United States with science-based knowledge to manage the risks and opportunities of change in the climate and related environmental systems. The CCSP is responsible for coordinating and integrating the research of 13 Federal agencies on climate and global change.